Water proton relaxation times are already being used extensively to characterize the malignant state. Ions of quadrupolar nuclei are relatively more sensitive to their environment than spin - 1/2 nuclei like protons. They, therefore, should be better suited as probes of the living state. Na23 nuclear magnetic resonance (NMR) spectroscopy will be examined as a possible method for distinguishing differences between normal and malignant cells. The purpose will be to develop Na23 spectroscopy as both a research and diagnostic tool for cancer studies. Na23 ions in tissues are easily detected in the NMR experiment. A complete description of the resonance phenomena in these heterogeneous systems is necessary for development of the technique in tissue studies. Two approaches will be followed in the proposed research. By using two model systems, erythrocytes and bacteria, we will characterize parameters influencing relaxation behavior of the Na23 ions. When the cells are dispersed in aqueous solutions, characteristics of Na23 ions resonances in different compartments can be studied. These models can then be used to explain the resonance behavior of Na23 ions in heterogeneous mixtures such as animal tissue. The nature of intracellular Na ions and extracellular Na ions interacting with the cell surface will be elucidated. The resonance characteristics will be examined as the intra- and intercellular environment is altered. The second approach will be to study Na23 ions resonances directly in tissue. Both normal and malignant tissue from animals will be examined. Several possible diagnostics procedures will be investigated. An extension of the model work will be to investigate the Na23 ions resonance characteristics in unicellular dispersions of normal and transformed cells obtained from cell culture.